Note 5 – Long-Term Debt

Carrying amounts of the Company’s long-term debt and their related estimated fair values as of September 30, 2013 and December 31, 2012 are disclosed in the following table. The fair values of the revolving credit facility (including commercial paper), the NPL revolving credit facility, and the variable-rate Industrial Development Revenue Bonds (“IDRBs”) approximate their carrying values, and are categorized as Level 1 (quoted prices for identical financial instruments) within the three-level fair value hierarchy that ranks the inputs used to measure fair value by their reliability. The market values of debentures (except the 6.1% Notes) and fixed-rate IDRBs are categorized as Level 2. The 6.1% Notes and NPL other debt obligations are categorized as Level 3 (based on significant unobservable inputs to their fair values). Fair values for the debentures, fixed-rate IDRBs, and NPL other debt obligations were determined through a market-based valuation approach, where fair market values are determined based on evaluated pricing data, such as broker quotes and yields for similar securities adjusted for observable differences. Significant inputs used in the valuation generally include benchmark yield curves and issuer spreads. The external credit rating, coupon rate, and maturity of each security are considered in the valuation, as applicable.


	September 30, 2013					December 31, 2012
	Carrying Amount			Market Value		Carrying Amount			Market Value
(Thousands of dollars)
Debentures:
Notes, 4.45%, due 2020	$	125,000		$	133,784	$	125,000		$	141,771
Notes, 6.1%, due 2041		125,000			142,243		125,000			165,779
Notes, 3.875%, due 2022		250,000			256,543		250,000			277,950
8% Series, due 2026		75,000			98,735		75,000			111,501
Medium-term notes, 7.59% series, due 2017		25,000			29,106		25,000			30,710
Medium-term notes, 7.78% series, due 2022		25,000			31,356		25,000			34,637
Medium-term notes, 7.92% series, due 2027		25,000			32,302		25,000			36,953
Medium-term notes, 6.76% series, due 2027		7,500			8,680		7,500			10,058
Unamortized discount		(3,259	)				(3,403	)

		654,241					654,097

Revolving credit facility and commercial paper		150,000			150,000		111,000			111,000

Industrial development revenue bonds:
Variable-rate bonds:
Tax-exempt Series A, due 2028		50,000			50,000		50,000			50,000
2003 Series A, due 2038		50,000			50,000		50,000			50,000
2008 Series A, due 2038		50,000			50,000		50,000			50,000
2009 Series A, due 2039		50,000			50,000		50,000			50,000
Fixed-rate bonds:
5.55% 1999 Series D, due 2038		—			—		8,270			8,375
5.45% 2003 Series C, due 2038		—			—		30,000			30,152
5.25% 2003 Series D, due 2038		20,000			20,095		20,000			20,571
5.80% 2003 Series E, due 2038		—			—		15,000			15,102
5.25% 2004 Series A, due 2034		65,000			61,914		65,000			66,955
5.00% 2004 Series B, due 2033		31,200			29,886		31,200			31,655
4.85% 2005 Series A, due 2035		100,000			94,475		100,000			101,184
4.75% 2006 Series A, due 2036		24,855			23,280		24,855			25,189
Unamortized discount		(2,808	)				(3,195	)

		438,247					491,130

NPL credit facility		4,000			4,000		41,562			41,562
NPL other debt obligations		44,956			44,977		20,721			20,991

		1,291,444					1,318,510
Less: current maturities		(11,052	)				(50,137	)

Long-term debt, less current maturities	$	1,280,392				$	1,268,373

In February 2013, a notice of mandatory tender was sent to holders of the Clark County, Nevada 5.45% Series 2003C and 5.80% Series 2003E IDRBs. These IDRBs (totaling $45 million) were subject to mandatory tender on March 1, 2013 at a price of 100% plus accrued interest, and the Company tendered these IDRBs to the trustee for cancellation immediately following the mandatory tender, thereby extinguishing this debt. The Company facilitated the redemption primarily from borrowings under its $300 million credit facility.

In September 2013, the Company redeemed at par the $8.27 million 5.55% 1999 Series D IDRBs originally due in 2038. The Company facilitated the redemption primarily from borrowings under its $300 million credit facility.

In October 2013, the Company issued $250 million in 4.875% Senior Notes at a 0.078% discount. The notes will mature in October 2043. A portion of the net proceeds were used to temporarily pay down amounts outstanding under the credit facility. The remaining net proceeds are intended to be used for general corporate purposes.